Fair Values of Assets and Liabilities - Schedule of Changes in Level 3 Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	$ 24,793	$ 37,812
Total gains or losses included in earnings	126	1,307
Total gains or losses included in other comprehensive income	2,391	2,268
Purchases	0	0
Issuances	0	0
Sales	(16,739)	(6,809)
Settlements	(1,252)	(1,035)
Transfers into Level 3	16,613	461
Balance, end of period	25,932	34,004
Pooled Trust Preferred Collateralized Debt Obligations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	23,373	22,980
Total gains or losses included in earnings	0	0
Total gains or losses included in other comprehensive income	2,391	2,268
Purchases	0	0
Issuances	0	0
Sales	0	0
Settlements	(1,252)	(740)
Transfers into Level 3	0	0
Balance, end of period	24,512	24,508
Equity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	1,420	1,420
Total gains or losses included in earnings	0	0
Total gains or losses included in other comprehensive income	0	0
Purchases	0	0
Issuances	0	0
Sales	0	0
Settlements	0	0
Transfers into Level 3	0	0
Balance, end of period	1,420	1,420
Loans Held For Sale [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	0	13,412
Total gains or losses included in earnings	126	1,768
Total gains or losses included in other comprehensive income	0	0
Purchases	0	0
Issuances	0	0
Sales	(16,739)	(6,809)
Settlements	0	(295)
Transfers into Level 3	16,613	0
Balance, end of period	0	8,076
Other Assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	0	0
Total gains or losses included in earnings	0	(461)
Total gains or losses included in other comprehensive income	0	0
Purchases	0	0
Issuances	0	0
Sales	0	0
Settlements	0	0
Transfers into Level 3	0	461
Balance, end of period	$ 0	$ 0